Figure 4.

Chemical Induction of Extracellular Invertase Cin1 Results in Delay of Senescence.

(A) Effect of the infiltration of tetracycline into detached leaves of a transgenic line expressing the extracellular invertase Cin1 under control of the tetracycline-inducible TetR promoter. The left leaf was infiltrated with an MS control solution, whereas the right one was infiltrated with the same solution containing tetracycline at a final concentration of 10 μg/L.

(B) Chlorophyll fluorescence image of the leaves shown in (A).

(C) RNA gel blot showing the accumulation of the Cin1 transcripts in leaves after 2 h of treatment with tetracycline in comparison to control leaves.

(D) Effect of the localized induction of Cin1 by spotting chlorotetracycline onto transgenic leaves. An MS solution containing either 0.02% Silwet (left control leaf) or the detergent plus chlorotetracycline (10 μg/L) (right leaf) was spotted onto the marked zones.

The results have been reproduced in five independent experiments with three independent transgenic lines, and representative results obtained with line NT35-7 are shown.